Composition for eliminating efflorescence in portland cement products

ABSTRACT

A composition comprising polyvinyl alcohol characterized by high-molecular weight and viscosity and very low solubility of insoluble in water, mixed with barium hydroxide or barium oxide, and added to Portland cement in the proportion ranging from 3/4 to 5 percent of the alcohol to 100 percent of the cement, effective to prevent bleeding of salts out of the cement and thereby markedly lessen or eliminate efflorescence in Portland cement products.

AU 112 EX United States Patent Ronzio et al.

[ Feb. 29, 1972 [54] COMPOSITION FOR ELlMlNATlNG EFFLORESCENCE INPORTLAND CEMENT PRODUCTS [72] inventors: Anthony R. Ronzio; Bernard T.Pull, both of Littleton, Colo.

[73] Assignee: Bio-Organic Chemicals, Inc., Denver,

Colo.

[22] Filed: Apr. 15, 1970 [2 l] Appl. No.: 28,951

[52] U.S. Cl ..l06/90, 106/314 [5 1] Int. Cl. ..C04b 13/24 [58] FieldofSearch ..l06/90,3l4, 315

[56] References Cited UNITED STATES PATENTS 3,030,258 4/1952 w er d.ies/s0 3,027,266 3/1962 2,576,955 l2/l95l Wikne 106/90 Ludwig 106/90Primary ExaminerTobias E. Levow Assistant Examiner-W. T. ScottAttorney-Bertha L. MacGregor [57] ABSTRACT 7 Claims, No DrawingsCOMPOSITION FOR ELIMINATING EFFLORESCENCE lN PORTLAND CEMENT PRODUCTSThis invention relates to a composition for substantially lessening oreliminating efflorescence in Portland cement products. The compositionprevents bleeding out of salts present in Portland cement which lead toefilorescence, and produces improved surface smoothness, enhancement ofcolor in products made of cement to which our composition has beenadded, and resistance to moisture penetration. The depth of color addedto the cement treated with this composition is greater than that ofcement untreated with our composition to which the same percentage ofcoloring agent has been added.

The invention is especially valuable when the treated concrete is usedfor fabricating building structures and parts of building structuressuch as steps, balustrades, decorative walls and the like, and fordecorative purposes involving the use of coloring pigments to impartcolor to the concrete.

Much effort has been directed in the past toward lessening oreliminating the efflorescence of concrete. Efilorescence is defined asthe migration of sparingly soluble salts, normally present in allPortland cement, to the surface of the concrete during the cure and postcure periods. Calcium sulfate is the main offender and is the majorcause of this effect. Calcium sulfate has limited solubility in water,namely, 0.241 g. in 100 ml. of water. Calcium hydroxide, which also ispresent to a smaller extent, will also bleed to the surface of curingconcrete and will deposit on the surface of curing concrete where itforms calcium carbonate with the carbon dioxide in the air. Calciumsolubility is 0.185 g. per 100 ml. of water.

The efilorescence appears as a white coating on the surface of concreteand imparts a mottled layer to the surface which is unattractive anddetracts from the appearance of the struc tures made with this material.When colored concrete is used for decorative purposes, the efflorescencedetracts from the appearance of the structure by its mottled and spottysurface coating.

The composition comprises polyvinyl alcohol having certaincharacteristics relating to viscosity, molecular weight and solubilityin water, and barium hydroxide or barium oxide, prepared as hereindescribed.

We have found that barium hydroxide or barium oxide reacts to form atype of compound known as a chelate" when it comes into contact withpolyvinyl alcohol. To prove this reaction, we determined the relativeviscosities of polyvinyl alcohol and of barium hydroxide in watersolutions, and the viscosity of a mixture of the polyvinyl alcohol andbarium hydroxide in water solution. A 2.00 percent solution in water orpolyvinyl alcohol (Elvanol Polyvinyl Alcohol 50-42" manufactured by E.l. DuPont de Nemours & Co.) was determined to have the relativeviscosity of 4.967; a 2.00 percent solution in water of barium hydroxidewas determined to have the relative viscosity of 1.0665; and a watersolution of 2.00 percent polyvinyl alcohol and 2.00 percent bariumhydroxide was determined to have the viscosity of 6.898, which isgreater than the sum of the viscosities of the two separate ingredients.

The composition of our invention is prepared by grinding Portlandcement, either clinker or previously powdered, polyvinyl alcohol andbarium hydroxide or barium oxide in a ball mill. Water and sand is addedto the resultant mixture to make concrete. A typical formula used as thebase for our composition is the following:

Polyvinyl Alcohol 1 g.

Barium Hydroxide 0.2 g. Portland Cement 100 3. Sand 300 g.

Water 44 cc.

The polyvinyl alcohol in this formula is 1 percent of the Portlandcement. Experiments were conducted in which the polyvinyl alcoholcontent was varied between /4 and 5 percent; the desired etfect began toappear at 36 percent (0.75 g. of polyvinyl alcohol to 100 g. Portlandcement).

In these experiments we used a light shade of Portland cement in theform of fine gray powder known as Type I or Grade A. Polyvinyl alcoholsvary in molecular weight and viscosity and hence in solubility in water.Experiments showed 5 that the best effect for out purposes is obtainedby the use of very sparingly soluble and insoluble alcohols, having highviscosity and high molecular weight. "Elvanol 72-60" is an example ofpolyvinyl alcohol well suited for our purposes. This polyvinyl alcoholand others useful in producing our composition are 100 percenthydrolyzed. They are manufactured by a process involving polymerizationof vinyl acetate and partial to complete hydrolysis of the intermediatepolyvinyl acetate to polyvinyl alcohol. Solution viscosity increaseswith increasing degree of polymerization.

Thus the completely hydrolyzed, highly viscous and insoluble, or veryslightly soluble, polyvinyl alcohols, together with the bariumhydroxide, mixed as described with Portland cement, in the proportionsstated, and added to sand and water to make concrete, result in aproduct characterized by absence of bleeding out of salts present in thePortland cement, freedom from efflorescence, easy troweling" for smoothsurfaces, enhanced color in the flnished product when a coloring agenthas been added, and high resistance to dried. The workability of thefinished product is such that a much smoother concrete is produced whichmakes it desirable for decorative construction. Freedom fromefflorescence is a valued quality in patios, buildings, walks,ornamental structures for gardens, and ather products, particularlywhere colored surfaces are desired.

The barium hydroxide polyvinyl alcohol complex compound combines withany calcium hydroxide formed during the curing of the concrete and alsowith that resulting from the reaction of barium hydroxide with calciumsulfate according to the following reaction Calcium belongs to the samegroup of elements as barium and accordingly both hydroxides react withpolyvinyl alcohol.

Our formulations may be used with polyvinyl alcohol insolubilizingreagents to further increase resistance to migration of water. This maybe desirable where the concrete is to be used for decorative paneling,decorative art work and the like. Many reagents may be used to enhancewater resistance. such as dimethylol urea, trimethylol melamine,glyoxal, inorganic salts, organic titanates,polyvinyl-methyl-ether/maleic anhydride I copolymer, the thio-organicacids (such as thioglycolic and thiopropionic acids) etc.

Adding the polyvinyl alcohol to the Portland cement clinker beforepulverizing, i.e., during the grinding, in preparing the Portland cementfor packaging, is the preferred method. The second choice is to ballmillthe polyvinyl alcohol with the Portland cement as it is purchased in thepowder fonn, This is necessary because of the low solubility of thegrade of polyvinyl alcohol used in our process.

It should also be noted that when the concentration of polyvinyl alcoholapproaches 1 percent based on Portland cement used, there occurs apronounced enhancement of surface color of the cured cement. This isimportant economically when pigment is added to color the concrete.

We claim:

-I. A composition for substantially lessening or eliminatingefflorescence in Portland cement products consisting of weight andpolyvin lalcohommm 65 low solubility or insoluble in water, and barium hdroxide or barium oxide, mixed together, in which thewvmwith the bariumhydroxide or oxide in the proportion of approximately 1 g. of thealcohol to 0.2 g. of the barium compound.

2. The composition defined by claim 1, in which the ingredients arecombined by grinding in a ball mill.

3. A composition for substantially lessening or eliminatingefi'lorescence in Portland cement products consisting essentially ofPortland cement and the composition of claim 1, 75 mixed together, inwhich the polyvinyl alcohol is combined penetration of moisture when theproduct has cured and relative viscosities of said separate components.

6. The composition defined by claim 3, in which the Portland cement isin clinker form and the ingredients are combined by grinding the cementclinker with the alcohol and barium to pulverize the mixture beforepackaging.

7. The composition defined by claim 3, in which the Portland cement isin powder form, and the ingredients are combined by milling together ina ball mill, preparatory to mixing with water to produce concrete.

2. The composition defined by claim 1, in which the ingredients arecombined by grinding in a ball mill.
 3. A composition for substantiallylessening or eliminating efflorescence in Portland cement productsconsisting essentially of Portland cement and the composition of claim1, mixed together, in which the polyvinyl alcohol is combined with thePortland cement in proportions within the range of approximately 1/2 to5 percent of the alcohol to 100 percent of the cement.
 4. Thecomposition defined by claim 3, in which the polyvinyl alcohol iscombined with the Portland cement in the proportion of approximately 1percent of the alcohol to 100 percent of the cement.
 5. The compositiondefined by claim 3, in which the polyvinyl alcohol and the bariumhydroxide or oxide when mixed together have a higher relative viscositythan the sum of the relative viscosities of said separate components. 6.The composition defined by claim 3, in which the Portland cement is inclinker form and the ingredients are combined by grinding the cementclinker with the alcohol and barium to pulverize the mixture beforepackaging.
 7. The composition defined by claim 3, in which the Portlandcement is in powder form, and the ingredients are combined by millingtogether in a ball mill, preparatory to mixing with water to produceconcrete.